The present invention relates to a method for transmitting information from a transmission site to a receiving unit. More particularly, the present invention relates to such a method for deciding whether to transmit the information, wherein the receiving unit is a two-way unit that sends a signal to the site, and wherein the decision to transmit is based on a comparison of the strength of the signal as received at the site against a signal threshold that differs based on the type of information that is to be transmitted.
In many transmission systems, a decision on whether to transmit information from a transmission site to a receiving unit is made based on whether the receiving unit will likely actually receive the information to be transmitted. In at least some of such transmission systems, the receiving unit is a two-way unit that can receive the sent transmission from the transmission site and that can also send signals back to the transmission site.
In such transmission systems, one way of deciding whether to transmit the information is to have the receiving unit send a signal to the transmission site, to then examine the strength of such sent signal as received at the transmission site, and to then make a judgment of the ability of the receiving unit to receive the transmitted information based on such signal strength. That is, the ability of the receiving unit to receive the transmitted information from the transmission site may be related, at least roughly, to the strength of a sent signal as received from such receiving unit at such transmission site. More particularly, if the signal strength is relatively strong, it is very likely that the receiving unit can receive the transmitted information. Correspondingly, if the signal strength is relatively weak, it is very likely that the receiving unit cannot receive the transmitted information.
One transmission system where such a decision is made is a cellular telephone system. In such a cellular telephone system, a mobile/cellular phone is a radio transceiver that is coupled to a cellular switch by way of a particular cellular tower that is also a radio transceiver, and the phone and the tower transmit to and receive from each other over pre-defined radio frequencies.
In such cellular telephone system, for example, a decision is made whether voice communications can commence between the tower and the phone based on the strength of a signal sent from the phone and received at the tower. Such signal strength as received at the tower, typically expressed in terms of decibels, is compared to a pre-defined signal strength threshold, also typically expressed in decibels, to determine whether the aforementioned voice communications can commence. More particularly, if the signal strength is stronger than the threshold, it is very likely that the phone can receive the voice communications from the tower, and communications may commence. Correspondingly, if the signal strength is weaker than the threshold, it is very likely that the phone cannot receive the voice communications from the tower, and communications may not commence.
As may be appreciated, the aforementioned cellular telephone system is expanding to include many additional services over and above mere voice communications. In particular, one additional service is data communications, wherein textual/ASCII messages are delivered to a particular cellular telephone for display on a display associated with such cellular phone. The display may be any appropriate display, but is typically a pixelated display such as an LCD screen on the surface of the cellular phone. Thus, a message is composed and sent from an appropriate source, is transmitted to the cellular phone by way of the cellular telephone system, and is then displayed by the cellular phone on the display associated therewith.
As with the decision on whether voice communications can commence, the decision on whether to transmit the message data from the tower to the phone is made based on the strength of a signal sent from the phone and received at the tower. More particularly, if the signal strength is above a pre-defined threshold, it is very likely that the phone can receive the message data from the tower, and transmission thereof may commence. Correspondingly, if the signal strength is below the pre-defined threshold, it is very likely that the phone cannot receive the message data from the tower, and transmission thereof may not commence.
An issue arises in that a typical cellular phone can reliably receive message data even under conditions where voice communications are inadvisable. That is, conditions may exist (1) where both voice communications and message data reception are advisable, (2) where only message data reception is advisable, or (3) where neither voice communications nor message data reception is advisable. Nevertheless, when determining whether voice communications can commence and also when determining whether message data transmission can commence, the aforementioned cellular system compares signal strength to only a single pre-defined threshold, where such threshold is calibrated for voice communications. As a result, message data transmission does not occur under condition (2), above, even though such message data transmission is in fact advisable.
Accordingly, a need exists for a method for deciding whether to transmit message data and for deciding whether voice communications can commence, wherein such decision is based at least in part on one threshold for message data transmission and another threshold for voice communications.
The present invention satisfies the aforementioned need by providing a method for determining whether to transmit from a first unit to a second unit, where the transmission is one of a first type and a second type. In the method, a signal from the second unit is received at the first unit, and the strength of the signal as received at the first unit is measured. A determination is made of whether the transmission is of the first type or the second type, and a first threshold is selected if the transmission is of the first type, or else a second threshold is selected if the transmission is of the second type. The measured signal strength is then compared to the selected threshold, and the transmission proceeds only if the measured signal strength exceeds the selected threshold.